wordpress如何正确自动获取中文日志摘要

function get_post_excerpt($post, $excerpt_length=240){
    if(!$post) $post = get_post();

    $post_excerpt = $post->post_excerpt;
    if($post_excerpt == ''){
        $post_content = $post->post_content;
        $post_content = do_shortcode($post_content);
        $post_content = wp_strip_all_tags( $post_content );

        $post_excerpt = mb_strimwidth($post_content,0,$excerpt_length,'…','utf-8');
    }

    $post_excerpt = wp_strip_all_tags( $post_excerpt );
    $post_excerpt = trim( preg_replace( "/[\n\r\t ]+/", ' ', $post_excerpt ), ' ' );

    return $post_excerpt;
}

<p><?php echo get_post_excerpt(); ?></p>